The present invention relates to an arrangement for the prevention of excess pressure in the housing of shut-off valves with varying pressure load where an independent chamber is provided with two facing openings which are connected via pressure lines to the pipe sockets connected to the shut-off valves, and which are closed by seals. The latter, in turn, are connected gas-tight via elastic elements, and where another pressure line discharges into the chamber space located outside the elastic element; this pressure line is connected to the interior of the housing of the shut-off valve.
An excess pressure safety device of the foregoing species is known from German Laid-Open Doc No. 2,041,722. This known arrangement can be further improved. The elastic element comprises a comparator. Because of the inherent rigidity of the metal compensator this excess pressure safety responds only at relatively high pressure differences so that the arrangement performs fully in the high-pressure range, but presents difficulties in the low-pressure range. In addition, the known safety device seals effectively only with pressure loads from one side in the direction of the housing of the shut-off valve. With load from the other side, a gap may form at the seating area of the seal; this gap creates a connection to the housing of the shut-off valve and puts it under pressure.
Accordingly, it is the object of the present invention to further develop the arrangement so that it seals on both sides and responds at low pressures also.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide an arrangement, as described, which may be readily maintained in service and which has a substantially long operating life.